A RAT wanders the subway tracks at Union Square in New York. The New York City Council is considering a proposal to create an emergency rat mitigation program for superstorm Sandy-impacted neighborhoods. But some experts aren’t so sure that Sandy’s supposed rat surge is for real, despite TV and newspaper reports about rats infesting parked cars and fleeing the East River waterfront for the brownstones of Brooklyn Heights — and exterminators enjoying a boom in business. But the city’s health department, which collects reams of data about the rat population and maps infestations looking for trends, said rodent complaints actually have declined since the late October storm, which was spawned when Hurricane Sandy merged with two other weather systems.